Configuring Network Policies to Restrict Pod Access

Notes and Constraints

• Only clusters that use the tunnel network model support network policies. There are two types of network policies:
  • Ingress: All versions support this type.
  • Egress: The cluster must be of v1.23 or later.
• Network isolation is not supported for IPv6 addresses.

Using Ingress Rules Through YAML

• Scenario 1: Controlled by a preset network policy, a pod can only be accessed by pods with specific labels.
  Figure 1 podSelector
  

  The pod labeled with role=db only permits access to its port 6379 from pods labeled with role=frontend. To achieve this, take the following steps:

  1. Create the access-demo1.yaml file.

     vim access-demo1.yaml

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-demo1
       namespace: default
     spec:
       podSelector:                  # The rule takes effect for pods with the role=db label.
         matchLabels:
           role: db
       ingress:                      # This is an ingress rule.
       - from:
         - podSelector:              # Only allows the access of the pods labeled with role=frontend.
             matchLabels:
               role: frontend
         ports:                      # Only TCP can be used to access port 6379.
         - protocol: TCP
           port: 6379

  2. Run the following command to create the network policy defined in the access-demo1.yaml file:

     kubectl apply -f access-demo1.yaml

     Expected output:

     networkpolicy.networking.k8s.io/access-demo1 created

• Scenario 2: Controlled by a preset network policy, a pod can only be accessed by pods in a specific namespace.
  Figure 2 namespaceSelector
  

  The pod labeled with role=db only permits access to its port 6379 from pods in the namespace labeled with project=myproject. To achieve this, take the following steps:

  1. Create the access-demo2.yaml file.

     vim access-demo2.yaml

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-demo2
     spec:
       podSelector:                  # The rule takes effect for pods with the role=db label.
         matchLabels:
           role: db
       ingress:                      # This is an ingress rule.
       - from:
         - namespaceSelector:        # Only allows the access of the pods in the namespace labeled with project=myproject.
             matchLabels:
               project: myproject
         ports:                      # Only TCP can be used to access port 6379.
         - protocol: TCP
           port: 6379

  2. Run the following command to create the network policy defined in the access-demo2.yaml file:

     kubectl apply -f access-demo2.yaml

     Expected output:

     networkpolicy.networking.k8s.io/access-demo2 created

Using Egress Rules Through YAML

Clusters of v1.23 or later that use a tunnel network support egress rules.

• Scenario 1: Controlled by a preset network policy, pods can only access specific addresses.
  Figure 3 IPBlock
  

  The pods labeled role=db only allow access to 172.16.0.0/16, excluding 172.16.0.40/32. To achieve this, take the following steps:

  1. Create the access-demo3.yaml file.

     vim access-demo3.yaml

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-demo3
       namespace: default
     spec:
       policyTypes:                  # This policy type must be specified for egress rules.
         - Egress
       podSelector:                  # The rule takes effect for pods with the role=db label.
         matchLabels:
           role: db
       egress:                       # This is an egress rule.
       - to:
         - ipBlock:
             cidr: 172.16.0.0/16    # Allows access to this CIDR block in the outbound direction.
             except:
             - 172.16.0.40/32        # Blocks access to this CIDR block. This CIDR block is in the allowed CIDR block.

  2. Run the following command to create the network policy defined in the access-demo3.yaml file:

     kubectl apply -f access-demo3.yaml

     Expected output:

     networkpolicy.networking.k8s.io/access-demo3 created

• Scenario 2: Controlled by a preset network policy, a pod can only be accessed by pods with specific labels, while this pod itself can only access specific pods.
  Figure 4 Using both ingress and egress
  

  The pod labeled with role=db only permits access to its port 6379 from pods labeled with role=frontend, and this pod can only access the pods labeled with role=web. You can use the same rule to configure both ingress and egress in a network policy. To achieve this, take the following steps:

  1. Create the access-demo4.yaml file.

     vim access-demo4.yaml

     File content:

     apiVersion: networking.k8s.io/v1
     kind: NetworkPolicy
     metadata:
       name: access-demo4
       namespace: default
     spec:
       policyTypes:
       - Ingress
       - Egress
       podSelector:                  # The rule takes effect for pods with the role=db label.
         matchLabels:
           role: db
       ingress:                      # This is an ingress rule.
       - from:
         - podSelector:              # Only allows the access of the pods labeled with role=frontend.
             matchLabels:
               role: frontend
         ports:                      # Only TCP can be used to access port 6379.
         - protocol: TCP
           port: 6379
       egress:                       # This is an egress rule.
       - to:
         - podSelector:              # The rule takes effect for pods with the role=web label.
             matchLabels:
               role: web

  2. Run the following command to create the network policy defined the access-demo4.yaml file:

     kubectl apply -f access-demo4.yaml

     Expected output:

     networkpolicy.networking.k8s.io/access-demo4 created

Creating a Network Policy on the Console

1. Log in to the CCE console and click the cluster name to access the cluster console.
2. Choose Policies in the navigation pane, click the Network Policies tab, and click Create Network Policy in the upper right corner.
   • Policy Name: Specify a network policy name.
   • Namespace: Select a namespace in which the network policy is applied.
   • Selector: Enter a label, select the pod to be associated, and click Add. You can also click Reference Workload Label to use the label of an existing workload.
   • Inbound Rule: Click to add an inbound rule. For details about parameter settings, see Table 1.

     

     Table 1 Adding an inbound rule

     Parameter	Description
     Protocol & Port	Select the protocol type and port. Currently, TCP and UDP are supported.
     Source Namespace	Select a namespace whose objects can be accessed. If this parameter is not specified, the object belongs to the same namespace as the current policy.
     Source Pod Label	Allow accessing the pods with this label. If this parameter is not specified, all pods in the namespace can be accessed.

   • Outbound Rule: Click to add an outbound rule. For details about parameter settings, see Table 2.

     

     Table 2 Adding an outbound rule

     Parameter	Description
     Protocol & Port	Select the protocol type and port. Currently, TCP and UDP are supported. If this parameter is not specified, the protocol type is not limited.
     Destination CIDR Block	Allow requests to be routed to a specified CIDR block (and not to the exception CIDR blocks). Separate the destination and exception CIDR blocks using a vertical bar (|). If there are multiple exception CIDR blocks, separate them using commas (,). For example, 172.17.0.0/16|172.17.1.0/24,172.17.2.0/24 indicates that 172.17.0.0/16 is accessible, but 172.17.1.0/24 and 172.17.2.0/24 are inaccessible.
     Destination Namespace	Select a namespace whose objects can be accessed. If this parameter is not specified, the object belongs to the same namespace as the current policy.
     Destination Pod Label	Allow accessing the pods with this label. If this parameter is not specified, all pods in the namespace can be accessed.

3. Click OK.